Do "git add" as a builtin

First try. Let's see how well this works.

In many ways, the hard parts of "git commit" are not so different from
this, and a builtin commit would share a lot of the code, I think.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git.c

@@ -50,6 +50,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
 		{ "count-objects", cmd_count_objects },
 		{ "diff", cmd_diff },
 		{ "grep", cmd_grep },
+		{ "add", cmd_add },
 	};
 	int i;